Cannot post graphql schema via curl

I want to use GraphQL language to update the schema on my Dgraph database. But following the quick start guide, I have encountered a show stopping error.

I tried to use curl -X POST localhost:8080/admin/schema --data-binary '@schema.graphql' with result: {"errors":[{"message":"resolving updateGQLSchema failed because input:1: Unexpected \u003cInvalid\u003e\n (Locations: [{Line: 3, Column: 4}])","extensions":{"code":"Error"}}]} regardless of what schema I use.

Is the documentation out of date on this topic as well?

Dgraph version : v21.03.1
Dgraph codename : rocket-1
Dgraph SHA-256 : a00b73d583a720aa787171e43b4cb4dbbf75b38e522f66c9943ab2f0263007fe
Commit SHA-1 : ea1cb5f35
Commit timestamp : 2021-06-17 20:38:11 +0530
Branch : HEAD
Go version : go1.16.2
jemalloc enabled : true

Review your Schema, use a simple one with a single type just to test. There’s nothing wrong with the admin API.